The coins, in $5, $10 and $20 denominations, date from 1847 to 1894. Most were minted in San Francisco.

They have a combined face value of about $27,000, but experts believe they could fetch $10 million or more.

Many are in pristine condition, including at least 14 coins that are considered the finest known for their date and mint mark.

A highlight from the hoard is an 1866-S No Motto Double Eagle, valued at close to $1 million.

The couple is planning to sell much of the collection.

Approximately 90% of the coins will go up on Amazon.com's "Collectibles" site, according to Don Kagin, of Kagin's, Inc., who is assisting the anonymous owners.

He told CNN the couple wants to donate some of the proceeds to charity.

"Basically they're thankful and they think it's wonderful that they're going to be able to save their property that they thought they might lose and, again, they want to give back to the community and to needy people," he said.

Collectors wanting a sneak peek can see some of the coins at the American Numismatic Association's 2014 National Money Show in Atlanta, which opens Thursday.

"Unlike other hoards and treasures, this one includes a great variety of coins struck over many different years, and many of the coins are still in pristine condition," Kagin said.

"And add to that a wonderful human interest story: this family literally found the pot of gold at the end of the rainbow."